Solar cell products convert light energy, such as that from the sun, to electrical energy. Solar cell products usually include a semiconductor substrate, such as a silicon substrate with a photoactive p-n junction, a front surface covered with a contacting grid having stripes and finger-like structures, and a back contacting surface covering the entire back of the solar cell. An antireflection coating can also be provided on the front surface of the solar cell reducing reflection of light for enhancing solar cell efficiency.
In general, solar cell products are equipped with a silicon substrate of monocrystalline or polycrystalline material which is cut into wafers, typically with side lengths of 125 to 156 millimeters or to round wafers having 150 to 200 millimeters of diameter. Main process steps of solar cell production include preparing of the p-n junction, where the substrate may be doped with p-type dopants, by doping with appropriate doping material, and contacting of the photovoltaic cell. Contacting of the photovoltaic cell can include covering the front surface with an electrically contactable grid and the back surface with a contact metallization. As such, configuration of metallic electrodes on the substrate's surface can be important to provide a good electronic contact and for a high power efficiency. For instance, small dimensions of metallic stripes and fingers for the front surface contacting grid reduce shadowing effects and enlarge areas of photovoltaic active regions of the solar cell.
Current structuring techniques for providing electrically contactable grids use a silver paste screen printing technique followed by a high temperature firing process. The firing process can cause some damage to the solar device due to excessive heating, however. Alternatively, a lithography masking technique for structuring a substrate method based on a stamping technology can be employed.